JP3113454B2 - Artificial knee joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial knee joint for replacing a knee joint whose function has been significantly reduced or lost due to a disease such as osteoarthritis and pain has increased.

[0002]

2. Description of the Related Art In a total knee arthroplasty, in order for a femoral side member to be firmly fixed to a femur, the bones on the inner surfaces of anterior wall and posterior wall and the distal joint surface of the femur contacting the inner surfaces of the anterior wall and the posterior wall. It is necessary to accurately perform the cut surface so as to obtain an appropriate press-fit between the bone and the bone so that an appropriate press-fit is obtained when the femoral side member is driven into the distal portion of the femur. Was.

However, the actual osteotomy accuracy is not enough to match this, and it is inevitable that some deviations and gaps between surfaces occur. For example, if the osteotomy angle is 5
°, with a normal osteotomy device, the angle is 1 ° ~
A variation of about 2 ° occurs. Therefore, a gap is generated between the bone and the femur side member, and the femoral member cannot be fixed firmly, or conversely, there is too much press-fit, and the femoral member is fixed by excessive press-fitting. The bone near the contact surface with the member is excessively compressed, and as a result, the stress transmission is biased, which may be a so-called stress shield, which may cause bone resorption. If the femoral side member is made of a metal material, even in such a case, the anterior wall and the posterior wall are relatively easily elastically deformed. Although it can be absorbed, when the femur side member is made of a brittle material such as ceramics, the fixing force with the femur must depend on the accuracy of the osteotomy, and if there is no accuracy In some cases, the use of bone cement was forced. Accuracy in such osteotomy has been a major problem.

A conventional artificial knee joint designed to solve such a problem is disclosed in Japanese Patent Application Laid-Open No. 63-279838.
As proposed in the publication, the femur side member is configured to fit so that the distal part of the femur is sandwiched between the inner surfaces of the anterior wall and the posterior wall, and the femoral side member contacts the distal end surface of the femur. There was an artificial knee joint in which a nail was formed on the inner surface of the sliding part in contact with the nail, and this nail was pressed into the femur to fix it to the femur without using bone cement. Further, Japanese Patent Application Laid-Open No. 64-68255
As proposed in the publication, a plate-shaped fin is formed on the inner surface of the sliding portion instead of the nail, and the plate-shaped fin is configured to be pressed into the femur, and the front wall and There was an artificial knee joint including a femoral side member formed on the inner surface of the rear wall and formed with a plurality of tooth-shaped protrusions having a height of about 1 mm and having a sawtooth shape to enhance the fixing force to the femur.

[0005]

However, in the above-mentioned conventional artificial knee joint, the nail or plate-like projection provided on the inner surface of the sliding portion of the femur side member is driven into the soft and weak cancellous bone of the femur. Therefore, the fixation force to the femur obtained by these is only an auxiliary force, and even if the initial fixation is obtained, it is necessary for long-term fixation in the body. Did not meet the dynamic requirements.

In view of the principle of replacement surgery, which minimizes the amount of osteotomy, the osteotomy for fitting the projection located substantially at the center of the distal end face of the femur as described above is originally used. This was an extra osteotomy and was not desirable.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to increase the fixing force of the femoral side member constituting the artificial knee joint to the femur and to reduce the thickness thereof, thereby reducing the amount of osteotomy of the femur. It is to provide an artificial knee joint.

[0008]

In order to solve the above problems,
The knee prosthesis of the present invention has a height or depth of at least 2 mm in a direction substantially perpendicular to the inner surface of the anterior wall and / or posterior wall of the femoral side member,
A convex protrusion and / or a concave groove having a length of 5 mm or more were formed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view of an artificial knee joint A as an example of the present invention, in which 20 is a tibial member that replaces a distal portion of a tibia, and 1 is a femoral side member that replaces a distal portion of a femur. .

The upper side of the tibial member 20 is the femoral member 1
The sliding part 4 located on the lower side is a sliding surface part 21 on which the rod slides, and a stem 22 having a rod shape is formed below the sliding surface part 21 so as to be inserted into the tibial cavity. .

The other femoral member 1 is composed of a plate-shaped front wall 2, left and right rear walls 3, 3 and a sliding portion 4 connecting these to form a substantially arcuate shape.

The outer surfaces of the front wall 2, the sliding portion 4 and the rear wall 3 of the femoral side member 1 have a smooth curved surface similar to the joint sliding surface in the normal state of the femur to be replaced. At the position interfering with the attachment portion of the anterior-posterior cruciate ligament located behind the femur, an intercondylar portion 5 is formed which divides the two rear walls 3 and a part of the sliding portion 4 at the center.

The inner surface 2a of the front wall has a flat surface, and in the vertical direction substantially at the center thereof, as a convex protrusion fitted into the bone, a pressing front protrusion 6 having a hemispherical horizontal cross section and a columnar shape is formed. Further, on the left and right of the pre-pressing projection 6, two pre-pressing grooves 7 having a hemispherical horizontal cross section are formed in parallel with the pre-pressing projection 6 as concave grooves for fitting a part of a bone. doing.

The inner surfaces 3a, 3a of the rear wall are flat surfaces, and in the vertical direction substantially at the center thereof, as a convex protrusion to be fitted into the bone, a columnar shape having a hemispherical horizontal cross section is formed. Protrusions 8, 8 are formed.

The size of the pre-pressing protrusion 6 and the pre-pressing groove 7 is 20 mm in length and the radius of the horizontal cross section is 5 mm. The size of the post-pressing protrusion 8 is 15 mm in length.
The radius of the horizontal section is 5 mm, at least 1-2 mm
The press-fitting margin is secured.

In the artificial knee joint A of the present invention configured as described above, the femoral member 1 is connected to the front wall inner surface 2a and the rear wall inner surface 3a.
The convex projections (protrusions 6 before pressing and projections 8 and 8 after pressing) and the concave grooves (grooves 7 and 7 before pressing) formed in 3a have a sufficiently large press fit as described above and a large area to contact the bone. Since the femoral members 1 are configured to be in contact with each other, the femoral member 1 is firmly fitted and fixed to the bone at this portion. Thereby, the femoral component 1
1 are generated around the convex protrusions and the concave grooves, particularly in the convex protrusions, and the stress is reduced in other portions accordingly. 2. As shown in FIG. 3, which is a cross-sectional view taken along the line YY in FIG. 1, the cross-sectional shape of the conventional femur side member 1 'is shown by the two-dot chain line, and the strength of the front wall 2 and the rear wall is also high. The thickness of the walls 3 and 3 is 1 to
It can be reduced by about 2 mm, and the amount of bone can be reduced accordingly.

The shapes of the convex protrusions 6 and the concave grooves 7 formed on the femur side member 1 are not limited to a semi-cylindrical shape, but may be a quadrangular prism shape or a triangular prism shape as shown in FIG. Momo is good.

In order for the femoral side member 1 to be firmly fixed to the femur, it is preferable that the height or depth of the convex projections and the concave grooves is 2 mm or more and the length is 5 mm or more. On the other hand, when the depth is smaller than 2 mm or the length is smaller than 5 mm, even if the initial fixation is obtained, excessive stress is generated in the convex projections and the concave grooves, and the bone tissue in contact with the convex projections and the concave grooves is reduced. It is not preferable because it may be absorbed.

Next, osteotomy for replacing the distal portion of the femur with the above-mentioned femoral member 1 constituting the artificial knee joint A of the present embodiment will be described. The perspective view of FIG. 5 shows a distal portion F of a cut femur for installing the above-mentioned femoral side member 1, and reference numeral 9 denotes a thigh against which the front wall inner surface 2 a of the femoral side member 1 abuts. The resection front face 10 of the bone distal portion F is a resection end face that abuts on the sliding part inner surface 4a of the femoral side member 1, and the resection front face 11 abuts on the rear wall inner surface 2a of the femur side member 1.

The resection front face 9 and resection end face 10 and the resection front face 10 and post-resection face 11 are substantially perpendicular to each other.
That is, the cut front surface 9 and the cut back surface 11 are cut so as to be substantially parallel to each other, and the cut front protrusions 1 corresponding to the cut front surfaces 7 and 7 of the femoral member 1 are fitted so as to fit into the grooves 7.
In order to fit the protruding projections (protrusions before pressing 6 and post-pressing projections 8) of the femoral member 1, the front and rear resection grooves 12, 14 and 14, 14, Is formed.

The vicinity of the center of the resection front surface 9 of the distal portion F of the femur, that is, the periphery of the pre-resection protrusion 6 is a portion where the bone cortex is most likely to remain. Fixing force increases.

The resection front projections 13 and 13 are semicircles having a radius of 5 mm in a horizontal cross section, while the resection front grooves 12 and post-resection grooves 14 and 14 are semicircles having a radius of 4 mm in a horizontal cross section. The anterior projections 13, 13 have a press fit of 1 mm into the femoral component 1, and the convex projections (pre-clamping projection 6, post-clamping projection 8) of the femoral component have a pre-resection groove 12 and a post-resection groove 14, respectively. , 14 with a press-fit margin of 1 mm.

FIG. 6 is a side view showing the distal portion F of the femur in a state where an osteotomy is performed to form the resection front groove 12 and the post-resection groove 14, and the tibia T is bent, and the distal portion of the femur is bent. Part F
A gage 15 which comes into contact with the cut front surface 9, the cut end surface 10, and the cut back surface 11 already cut into the bone is inserted into
A drill D is acted on from a drill guide hole 16 provided upright in 5 to form semicircular grooves, ie, a cut front groove 12 and a cut rear groove 14, at predetermined positions.

According to this method, the drill guide hole 1
Since the bone is cut by drill D guided to 6, ± 5
The excision front face groove 12 and the post-excision face groove 14 can be formed with an accuracy of about 0 μm or less. Therefore, the convex protrusions (the protrusion 6 before press-fitting and the protrusion 8 after press-fitting,
8) and the concave grooves (grooves 7, 7 before press-fitting) and the bones
Since the fitting is performed in close contact with a press-fit of about 1 mm, even a technically unskilled operator can fix the femoral side member 1 to the femur with a sufficient fixing force without using bone cement. .

It is preferable that the total number of the convex protrusions and / or the concave protrusions is 2 to 10. On the other hand, a sufficient fixing force cannot be obtained in the femoral component 1 having only one convex projection and / or concave projection, and a required amount of osteotomy becomes too large with ten or more convex projections and / or concave projections. Not preferred.

It is not always necessary to form the convex and / or concave projections on both the front wall inner surface 2a and the rear wall inner surface 3a, but only on the front wall inner surface 2a or only the rear wall inner surface 3a. Is also good.

[0027]

As described above, the knee prosthesis of the present invention has a convexity having a height or depth of at least 2 mm and a length of at least 5 mm in the direction substantially perpendicular to the inner surface of the anterior wall and / or posterior wall of the femoral side member. By forming the protruding protrusions and / or the concave grooves, the femoral side member can be easily and firmly fixed to the femur without using cement, and the thickness can be reduced. The cutting amount can be minimized. Therefore, it is possible to provide an artificial knee joint that is safe for a living body and that can withstand long-term use.

[Brief description of the drawings]

FIG. 1 is a perspective view of an artificial knee joint according to the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a sectional view taken along line YY of FIG. 1;

FIG. 4 is a sectional view taken along line XX of FIG. 1;

FIG. 5 is a perspective view of a distal portion of a femur.

FIG. 6 is a side view of a distal portion of a femur.

[Explanation of symbols]

 A: Artificial knee joint D: Drill F: Femur distal part 1: Femur side member 2: Anterior wall 2a: Anterior wall inner surface 3: Rear wall 4: Sliding part 4a: Sliding part inner surface 5: Intercondylar part 6: Pre-press projection 7: Pre-press groove 8: Post-press projection 9: Resection front 10: Resection end face 11: Resection rear face 12: Resection front groove 13: Resection front projection 14: Resection rear projection 15: Gauge 16: Dolli guide hole 20 : Tibial member 21: Sliding surface 22: Stem

Claims (1)

(57) [Claims] 1. A tibial member for replacing a distal portion of a tibial bone, an anterior wall for replacing an anterior surface of a joint surface of a distal femur, and medial and lateral condyles behind a joint surface of the distal femur. A rear wall that replaces, and functions as a main joint surface connecting the front wall and the rear wall, a femoral side member comprising a generally arcuate sliding portion,
An artificial knee joint comprising a protruding protrusion and / or concave groove having a height or depth of 2 mm or more and a length of 5 mm or more in a direction substantially perpendicular to the inner surface of the front wall and / or the rear wall. .